Are you working on your own dapp? Security experts from Nethemba wrote a great list of mistakes you should avoid in the process of coding your own smart contract. Be aware of these vulnerabilities!

You can also build your Ethereum dapp on ZeppelinOS which is finally live. ZeppelinOS is an operating system designed specifically for smart contracts. It provides an on-chain set of upgradeable standard libraries, and an incentive structure to continually upgrade and patch itself.